Title: Using Metal Cutting Processes and
1 Lesson 5
- Using Metal Cutting Processes and
- Techniques
2Next Generation Science/Common Core Standards
Addressed!
- CCSS.EL A Literacy.RST.9-10.1 Cite specific
textual evidence to support analysis of science
and technical texts, attending to the precise
details of explanations or descriptions. - CCSS.ELA Literacy. RST.9-10.3 Follow precisely a
complex multistep procedure when carrying out
experiments, taking measurements, or performing
technical tasks, attending to special cases or
exceptions defined in the text. - CCSS.ELA Literacy.RST.11-12.1 Cite specific
textual evidence to support analysis of science
and technical texts, attending to important
distinctions the author makes and to any gaps or
inconsistencies in the account. - CCSS.ELA Literacy.RST.11-12.3 Follow precisely a
complex multistep procedure when carrying out
experiments, taking measurements, or performing
technical tasks analyze the specific results
based on explanations in the text
3Bell Work/Student Learning Objectives
- 1. Identify the equipment used when cutting cold
metal. - 2. Describe the processes and techniques used
when cutting cold metal. - 3. Identify the equipment used when cutting hot
metal. - 4. Describe the processes and techniques used
when cutting hot metal. - 5. Identify safety practices that should be
observed when cutting cold and hot metal.
4Terms
- Cape chisels
- Diamond point chisels
- Double cut file
- File
- Flat chisels
- Hacksaw
- Rasp
- Round nose chisels
- Single cut file
- Snips or shears
5Interest Approach
- There are 2 pieces of metal that are the same
size and thickness in the ag. mechanics lab. - Student 1 will be using a hacksaw to cut the
piece of metal. - Student 2 will be using a gas torch to cut the
piece of metal. - Will there be any differences?
- Advantages/disadvantages?
6What equipment is used when cutting cold metal?
7Cold Metal Cutting
- Cold metal may be cut with a hacksaw, cut-off
saw, band saw, bolt cutter, file, snips or
shears, or a cold chisel.
8Cold Metal Cutting
- Cold metal cutting tools are divided into
categories depending on their power source,
either hand or power. - The operator provides the power for operating the
hand tools, while power tools rely on a source
other than the operator for power.
9 Hacksaw
- A tool often used for cutting metal is the
hacksaw. - A hacksaw is a saw with a frame and a blade
designed for cutting metal. - They are designed so new blades can be installed
easily.
10Hacksaw
- Select the proper blade for the job to be
completed. - Hacksaw blades vary in type and size.
- All-hard blades are hardened throughout and are
used for sawing heavy work, tool steel, cast
iron, and brass.
11Hacksaw
- Only the teeth are hardened on the flexible
blades. They are used for sawing light and hollow
materials. - Hand hacksaw blades are made in 8 inch, 10 inch
and 12 inch lengths, with 14, 18, 24, or 32 teeth
per inch.
12Hacksaw
- Hacksaw blades can be purchased with an undulated
(wavy), alternate, or raker tooth arrangement
pattern. - Lower quality blades have undulated teeth
arrangement.
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14Bolt cutters
- Bolt cutters provide a fast and efficient method
of cutting bolts, rods, and other small metals. - The capacity of the bolt cutter is stamped on
ranges from 3 /16 inch to ¾ inch.
15Files
- A file is made of hardened high-carbon steel,
with flat or rounded surfaces that are made rough
with teeth or grit. - They are used for smoothing surfaces or
sharpening metal objects.
16 Files
- Files come in various shapes and sizes and in
various sizes of cuts (chisel teeth). - A file with straight teeth all going in the same
direction is a single cut file. - A file with teeth in two directions is known as a
double cut file.
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18Parts of a File
19 Files
- A file with sharp pointed teeth is known as a
rasp. - Both single cut and double cut files are made in
different degrees of coarseness. - Rough, middle, bastard, second cut, and smooth
are examples of coarseness. - The coarseness also varies with the length of the
file.
20Cuts of a File
21 Files
- Common files are flat, rasp, half round, round
bastard, and taper triangular. - Flat files are used for smoothing both wood and
metal. - Rasp cut files are used for smoothing coarse wood
work. - Half round files are used for both metal and wood.
22 Files
- Round bastard files are used for enlarging and
smoothing holes. - Taper triangular files are used for filing saws
or cleaning threads.
23Shapes of a File
24Care of a File
25Snips or shears
- Snips or shears are large scissor-like tools for
cutting sheet metal and fabrics, and are divided
into regular, or compound aviation. - Regular snips or shears are used for light
cutting, while compound or aviation are used for
heavy cutting. - Snips or shears are used for cutting straight,
left-hand, or right-hand curves.
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27Cold Chisels
- When using a cold chisel to cut metal, the chisel
must be harder than the metal it is intended to
cut. - The four standard shapes for cutting edges for
cold chisels are flat, cape, diamond-point, and
half-round nose.
28 Cold Chisels
- 1. Flat chisels are used for chipping, removing
metal from a flat surface, and cutting sheet
metal.
29 Cold Chisels
- 2. Cape chisels are used for cutting narrow, flat
grooves and slots.
30Cold Chisels
- 3. Round nose chisels are used to cut concave
grooves.
31 Cold Chisels
- 4. Diamond point chisels are used to cut v-shaped
grooves.
32Cold Chisels
- 1. Flat chisels are used for chipping, removing
metal from a flat surface, and cutting sheet
metal. - 2. Cape chisels are used for cutting narrow, flat
grooves and slots. - 3. Round nose chisels are used to cut concave
grooves. - 4. Diamond point chisels are used to cut v-shaped
grooves.
33F. Metal cutting power tools are reciprocating
hacksaws, band saws, cut-off saws, and shears.
34The Power Hacksaw
- The power hacksaw has a reciprocating movement
which operates similar to the hand hacksaw,
however it cuts much faster. - The frame holds a rigid blade which is ¾ inch to
1 inch wide and 12 inches to 18 inches long. - Blades are available with fine to coarse teeth.
35Horizontal Band Saws
- Horizontal band saws have a blade that travels on
wheels and moves through rollers and guides, and
saws parallel to the ground. - Blade movement is forward at all times, so it
cuts continuously, which results in faster
cutting than the power hacksaw.
36Metal Cut-off Saws
- Metal cut-off saws, also known as chop saws, use
a circular blade lowered into the material that
is being cut. - The cutting blade is an abrasive disc that
provides a straight clean cut.
37The Power Shear
- The power shear can cut flat, angle, and other
structural steel faster and cleaner than by hand
or by power saw.
38What processes and techniques are used when
cutting cold metal?
39Hacksaws are made to cut metal.
- 1. Be sure safety glasses are worn.
- 2. Select a blade with enough teeth per inch so
that two or three teeth are in contact with the
metal at all times. - There must be few enough teeth to the inch to
allow the gullets to carry off the chips without
clogging.
40Hacksaws
- 3. Fasten the blade into the hacksaw frame with
the teeth pointing away from the handle of the
saw. - Make sure the blade is fastened securely so that
it will not twist and break.
41Installing a Hacksaw Blade
42Installing a Hacksaw Blade
43Hacksaws
- 4. Mark the stock at the point at which it is to
be cut. - 5. Place the stock in the vise, with the mark
about ½ inch from the jaws. - Sawing close to the jaws of the vice makes the
sawing easier because the piece is held firmly
and does not spring back and forth.
44Hacksaws
- 6. Place the saw on the mark and then pull it
toward you using little pressure to start the
kerf. - To help get the saw started in the proper place,
a notch can be cut at the mark with a file.
45Hacksaws
- 7. Apply slight pressure on the forward strokes
of the hacksaw, and release the pressure on the
return strokes to insure proper cutting and to
lessen the danger of breaking the blade of the
saw.
46Hacksaws
- 8. Run the saw evenly, using long strokes, with
all the teeth cutting to prevent wear on a small
portion of the blade, thus shortening the life of
the blade.
47Hacksaws
- 9. Thin metal can be cut more easily with a
hacksaw if a thin piece of wood is clamped on
each side of the metal. - Saw through the metal and wood pieces
simultaneously.
48Similar procedures should be followed when using
a horizontal band saw.
49Chisels
- Chisels are made to cut cold metal. These will
usually cut any metal which can be filed. - 1. Be sure safety glasses are worn.
- 2. Mark the material to be chiseled.
- 3. Select the correct chisel for the job.
- Make sure the edge is in good condition.
50Chisels
- 4. Place the stock in a vise or clamp it to the
table. Watch the edge of the chisel as you work. - 5. Sharp, quick blows are best. Reset the chisel
after each blow. - 6. The angle of the cutting edge of a chisel
should be approximately 65 degrees with the
cutting edge slightly rounded.
51Chisels
- 7. In removing metal, hold the chisel at an angle
that will keep the surface of the work and the
lower bevel of the chisel parallel. - 8. When cutting heavy, round stock, cut halfway
through, then turn the stock and make the rest of
the cut from the opposite side.
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53 Files
- Small amounts of metal may be removed where
needed with a file. - 1. Be sure safety glasses are worn.
- 2. Mark the material to be filed.
- 3. Place the stock in a vise or clamp it to the
table. - 4. Select the correct file for the job to be
done.
54 Files
- 5. File teeth usually slant toward the point of
the file and therefore cut only on the forward
stroke. - 6. A handle should be placed on the tang of the
file. - 7. Hold the handle of the file against the palm
of the hand, with the thumb on the top of the
handle.
55 Files
- 8. Hold the point of the file with the thumb and
index finger of the other hand. - 9. Use pressure on the forward stroke only, and
use only enough pressure to make the file cut
evenly. - Do not bear down hard on a new file, or the teeth
will be ruined. - A new file should be broken in by using it first
on brass or bronze.
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57Files
- 10. Lift the file on the return stroke when using
s single cut file. A double cut file will cut in
both directions. - 11. Do not take more than 30 to 40 strokes a
minute. - Excessive speeds will ruin both the file and the
work.
58Files
- 12. Rubbing chalk on a file before it is used
will help to prevent it from becoming clogged. - If a file becomes clogged, it may be cleaned with
a file card, pick, and brush.
59 Files
- 13. Do not use a file on material harder than the
file. - 14. Store files in separate holders to prevent
their rubbing together or knocking against other
tools. - The teeth are brittle and thus are easily dulled
or broken.
60Snips or shears
- Snips or shears are used for cutting sheet metal
and fabrics. - 1. Be sure safety glasses are worn.
- 2. Mark the material to be filed.
- 3. Place the stock in a vise or clamp it to the
table. - 4. It is advisable to wear gloves when handling
and working with sheet metal.
61Snips or shears
- 5. Select the correct shears for the job to be
done. - Select a pair of shears that are sharp and free
of nicks. - 6. A piece of scrap should be cut first to be
sure the shears are heavy enough.
62Snips or shears
- 7. Shears are used like scissors.
- For them to work well, the metal must curl or
lift up and out of the shear as the cut
progresses.
63Cutoff saws
- Cutoff saws are the most common method of cutting
steel in Agriculture Mechanics classes. - 1. Be sure safety glasses are worn. Hearing
protection may also be needed. - 2. Mark the material to be cut.
64Cutoff saws
- 3. Be sure the saw is properly adjusted and the
blade in the machine is designed to cut the kind
of material to be cut. - 4. Place the stock on the table of the saw and
use the vise or clamp to hold it securely.
65Cutoff saws
- 5. Hold the handle with one hand and turn the
switch on. - 6. Lower the saw slowly into and through the
material to be cut using a slow deliberate
motion.
66Cutoff saws
- 7. After the cut is made, let the saw rise, and
turn off the switch. - 8. After the saw has stopped turning, release the
handle and remove the material.
67The Power Hacksaw
- The power hacksaw is very useful in the
agricultural mechanics shop. - 1. Be sure safety glasses are worn.
- 2. Mark the material to be filed.
- 3. Be sure the saw is properly adjusted and the
blade in the machine is designed to cut the kind
of material to be cut.
68The Power Hacksaw
- 4. Place the frame in the raised position.
- 5. Adjust the vise on the machine to hold the
metal at the desired angle. - 6. Position the metal in the vise on the machine
and tighten securely.
69The Power Hacksaw
- 7. Turn on the machine.
- 8. Lower the frame slowly and carefully until the
blade is on the stock and starting to cut. - 9. If equipped with coolant, turn it on during
the duration of the cut. - 10. Stay near the machine while it is cutting.
70The Power Hacksaw
- 11. Switch off the machine when the cut is
finished if it does not turn off automatically. - 12. Remove all scrap metal and clean up all metal
dust and coolant.
71What equipment is used when cutting hot metal?
72Hot cutting is most often performed with an
oxy-fuel gas torch, or plasma cutter.
73Fuel gas welding
- 3. When oxygen strikes a preheated metal surface,
it causes the metal to burn or oxidize. - The oxygen combines with the heated iron to form
a molten metal and slag which flows or is blown
away, exposing more metal to the oxygen jet.
74Fuel gas welding
- 4. The tip of a cutting blowpipe has several
small holes (orifice) located around a larger
hole in the center of the tip. - The small holes permit the oxyacetylene mixture
to pass through them. - They provide flames to preheat the metal before
it is cut.
75Fuel gas welding
- The large hole in the middle of the tip supplies
a jet of oxygen under high pressure that does the
actual cutting after the metal is preheated to a
red heat.
76The arc welding electrode
- The arc welding electrode can be used for cutting
metal. - An electrode is useful for cutting cast iron, for
cutting in inaccessible places, and for cutting
small jobs.
77The arc welding electrode
- The use of an arc is usually considered to be the
best method of cutting cast iron, because cast
iron does not oxidize with heat. - To be cut, cast iron must be melted and the
electric arc melts metal as a means of cutting it.
78The arc welding electrode
- Cutting metal with an electrode is fast, but the
cut is not smooth. - Steel melts at approximately 2,600F, while the
heat generated by the electric arc is 6,500F.
79Plasma arc cutters
- Plasma arc cutters work by sending an electric
arc through a gas that is passing through a
constricted opening. - The gas can be shop air, nitrogen, argon, oxygen,
etc. - This elevates the temperature of the gas to the
point it enters a fourth state of matter, plasma.
80Plasma arc cutters
- 1. As the metal being cut is part of the circuit,
the electrical conductivity of the plasma causes
the arc to transfer to the work. - 2. The restricted opening or nozzle the gas
passes through causes it to squeeze by at a high
speed. - The high speed gas actually cuts through the
molten metal.
81Plasma arc cutters
- The gas is also directed around the perimeter of
the cutting area to shield the cut. - 3. Plasma cutters are ideal for cutting mild and
stainless steel, aluminum, brass and copper. - Virtually no heat spread is given.
- This means almost no distortion or discoloration
occurs to the material being cut.
82Plasma arc cutters
- 4. Computer numerically controlled (CNC) plasma
cutters fully automate the shape production
process. - These machines can be relatively inexpensive
units that operate by personal computers. - Those used with expensive, limited production
computers made specifically for running the
burning machines may cost as much as 100,000.
83Fuel Gas Cutting Procedure
- Place the piece of steel on the welding table so
that the mark clears the edge of the table by at
least one inch. This should eliminate damaging
the table surface.
84Fuel Gas Cutting Procedure
- Be sure safety glasses are worn. Put on a gas
welding face shield or goggles, and gloves. - Light the cutting blowpipe.
85Fuel Gas Cutting Procedure
- Follow the same procedures for lighting,
adjusting, and shutting down the blowpipe that
were given in the previous lessons. - An addition to the lighting procedure is to
depress the cutting-oxygen valve lever and check
to see that a neutral flame is present. - If necessary, adjust the pre-heat oxygen valve
until a neutral flame is maintained when the
cutting-oxygen valve is open.
86Fuel Gas Cutting Procedure
- Hold the blowpipe with the nozzle perpendicular
to the surface of the metal and with the inner
cones of the preheating flames at the edge of the
piece of steel and about 1 /16 inch above the
chalk line.
87Fuel Gas Cutting Procedure
- Hold the blowpipe steady at this spot until the
steel becomes a bright red, then slowly press
down the cutting-oxygen valve lever. When the
metal has been pierced tilt the torch so that the
tip is pointing in the direction of travel and
begin to move slowly. - A bright red color indicates that the steel is
near the melting point. - Move the blowpipe slowly along the cut-off line,
cutting completely through the metal as the
cutting proceeds.
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89Arc Welding cutting Procedure
- Cutting with the arc welding electrode requires
the use of 30 percent more amperage than would be
used for welding. - Be sure safety glasses are worn.
- Put on a electric welding face shield and gloves.
90Arc Welding cutting Procedure
- When cutting flat metal which is thicker than the
electrode, the metal to be cut is placed in a
flat or horizontal position. - Strike the arc where the cut is to be made, and
allow the heat of the arc to form a crater of
molten metal.
91Arc Welding cutting Procedure
- Move the electrode back and forth in a sawing
motion to force the molten metal from the cut or
kerf.
92Arc Welding cutting Procedure
- A downward pushing motion coupled with a quick
upward motion helps to force the molten metal
from the cut. - Since arc cutting is done by melting the metal,
the motion of the electrode and the position of
the work should assist the molten metal to fall
out of the cut.
93Arc Welding cutting Procedure
- When cutting round stock, start at an outer edge
of the stock so that the molten metal can escape. - Follow the same procedures as when cutting flat
stock. - When the cut reaches the center of round stock, a
new cut is made from the opposite side.
94Arc Welding cutting Procedure
- In cutting holes, burn a hole by pushing the
electrode through the metal. - Use a short arc and push the tip of the electrode
into the crater of molten metal. - If a larger hole is needed than the hole burned
by the electrode, move the electrode around the
edge of the hole in a widening circle until a
hole of the desired size is obtained.
95Plasma Cutting Procedure
- A plasma cutter is operated very similar to the
oxyacetylene torch in that the tip does not touch
the workpiece.
96Plasma Cutting Procedure
- 1. Be sure safety glasses are worn.
- 2. Turn the machine on and set it to
manufacturers recommendations. - 3. Put on an electric welding face shield and
gloves.
97Plasma Cutting Procedure
- 4. Hold the plasma arc gun with the contact tip
perpendicular to the surface of the metal at the
edge of the piece of steel and no closer than 1
/16 inch above the cut-off line.
98Plasma Cutting Procedure
- 5. Depress the trigger on the gun and move slowly
along the cut-off line, cutting completely
through the metal as the cutting proceeds. - 6. When the cut is complete let loose of the
trigger to extinguish the arc.
99What safety practices are observed when cutting
cold and hot metal?
100V. When cutting cold and hot metal, observe the
following safety practices. Obtain the
instructors permission before using any tool or
machine. Follow these guidelines
101Safety Guidelines
- A. Keep the work area and tools clean.
- Dirty, greasy, and oily tools and floors can
cause accidents. - Clean and put away all unneeded tools and
materials. - Clean up oil spills and scrap metal from the
floor and equipment. - Keep paths to exits clear.
102Safety Guidelines
- B. Wear industrial quality eye protection to
protect eyes from sparks and metal chips. - C. To protect against burns, wear clothing such
as coveralls, high-top shoes, leather aprons, and
leather gloves. - Remove all paper from pockets, and wear cuffless
pants.
103Safety Guidelines
- D. Protect hair and scalp by restraining long
hair and wearing a cap. - E. Loud talking as well as pushing, running, and
scuffling while working with hot metal can cause
serious accidents. - Keep your mind on your work!
104Safety Guidelines
- F. In the event of an emergency, all students
involved in or observing the emergency should
call for help immediately. - You should know the location of fire
extinguishers and fire blankets and how to use
them. - You should also know the approved procedure for
exiting the laboratory.
105Safety Guidelines
- G. Report all injuries or accidents to the
instructor immediately, no matter how slight. - H. Always use the right size tool and only for
its intended purpose. - I. Be certain that stock to be worked is securely
fastened in a vise or by clamps to prevent tools
from slipping.
106Safety Guidelines
- J. Mount vises, anvils, and clamps securely for
metalwork. - K. Work in a well-ventilated area. Fumes and
intense heat are a part of hot metalwork and
require that work be done outdoors or in a
forced-ventilated area.
107Safety Guidelines
- L. When lifting heavy objects, obtain help.
- Lift with the legs and not the back.
- Straining to lift heavy objects can cause serious
injury.
108Safety Guidelines
- M. To avoid the possibility of accidental burns,
keep hot metal in a safe place until it cools. - Test metal with moistened finger tips before
actually touching it. - Use tongs or pliers for handling hot metal.
109Safety Guidelines
- N. Before leaving the laboratory or work station,
make certain the heat source is shut off and
cool. - O. Do not perform hot metalwork on wood
floors/tablers or near flammable materials. - Never work on containers that have been used for
storage of combustible material.
110Safety Guidelines
- P. Keep cables and hoses from coming in contact
with hot metal and sharp objects. - Never point a flame at cables or hoses.
111Review/Summary
- 1. Identify the equipment used when cutting cold
metal. - 2. Describe the processes and techniques used
when cutting cold metal. - 3. Identify the equipment used when cutting hot
metal.
112Review/Summary
- 4. Describe the processes and techniques used
when cutting hot metal. - 5. Identify safety practices that should be
observed when cutting cold and hot metal.
113The End!